240 



VITAMINS 



thenic acid is involved in human nutrition, although clinical experience 

 in this direction is still rather meager. 



Pantothenic acid functions as part of a coenzyme (coenzyme A or Co yl) 

 in a system which brings about the condensation of acetic and oxalacetic 

 acids to form citric acid, one of the steps of the citric acid cycle (p. 330). 

 In fact Co A is probably needed for all metabolic reactions of the "two 

 carbon fragment" (acetic acid or some closely related substance) pro- 

 duced during the oxidation of fats and carbohydrates in the body. Since 

 this fragment is also used for the biological production of fats, steroids, 

 acetyl choline, and probably many other products, the indispensable nature 

 of pantothenic acid for living organisms is easily understandable. 



Chemical nature 



Pantothenic acid is a peptide-like compound composed of y8-alanine 

 united through an amide linkage to an hydroxy acid. The complete 

 structural formula is: 



T' ? 



CH2— C— CH— C— NH— CH, — CHj— COOH 



III 

 HO H3C OH 



Pantothenic acid, C9H17O5N 



The details of this formula were worked out in 1940, and the synthesis 

 of the vitamin was also accomplished in the same year. The substance 



■ ■ ' ■■■' ■' >'/ A: ^1 



1r J<" 





<•■'. _„„'**_.// .-^ 



Courtesy of Merck & Co., Inc. 

 Fig. 9-11. Pantothenic acid. 



